Just ran across some notes Ive used to install jib sheet rails. Maybe they can help some older questions that have come up. Generally: primary tracks should be 8 degrees from center line for a race boat, 10 degree for a cruising boat. For a #3 & #4 genoas 9 degrees race boat, 13 degrees for most cruising boats. To find angles measure 120 inches back from bow at the center line of the boat. 21 inches to port or starboard equals 10 degrees. Every two inches either direction = one degree. Hopes this helps.